1. Field of the Invention
The present invention relates to a library apparatus designed to hold recording media such as magnetic tape cartridges within cells defined in a storage cabinet, for example.
2. Description of the Prior Art
A magnetic tape library apparatus is generally known, for example, as disclosed in Japanese Patent 3380694. Such a magnetic tape library apparatus includes cabinet storages each defining cells. The individual cell contains a magnetic tape cartridge. A self-propelled carrier robot transports the magnetic tape cartridge between a magnetic tape drive and the individual cell.
Now, assume that an earthquake causes the magnetic tape cartridge to fall off the cell. When the magnetic tape cartridge falls into the movement path of the carrier robot, the magnetic tape cartridge gets run over by the carrier robot in some cases. This results in damage to the magnetic tape cartridge. Once such a magnetic tape cartridge gets damaged, it cannot easily be repaired, so that information recorded in the magnetic tape cartridge is lost. When the magnetic tape cartridge has fallen off, it is desirable to stop the carrier robot as soon as possible. A conventional magnetic tape library apparatus is allowed to notice the fall of the magnetic tape cartridge only when the carrier robot accesses the cell, as disclosed in Japanese Patent 3380694.